Sorry to double post but I figured out the problem (or at least I think I figured out the problem) and fixed it. Initially my folders went exported -> myitem -> swap_myitem and before I even got to the part of the tutorial where it goes into making the swappable build thing in spriter, I caught the mistake and fixed it. however, by that point, I had also already run the game with line 4 of myitem.lua commented out and an anim zip for the swap_myitem had been built based on the old folder i guess, and something about that was messing up the whole thing. I deleted the old anim and built a new one with the correct folder layout and voila, the item shows up when equipped now. hopefully this can help any of the other people who have come across this and found themselves confused over why the answers earlier in the thread weren't helping them.